I have a 3 phase ess system with one multiplus II 48/5000 GX and two multiplus II 48/5000, cerbo gx, Pylontech battery. Lately I got a low battery (Multiplus switches to pass-thru) warning on the multiplus but not on the cerbo, SoC is the same as on the cerbo (e.g. 85%). When I cut mains multiplus switches to discharging. When I restart the multiplus everything is working fine again. After some time the issue occurs. Yesterday it did not work, no power, I think it thinks it is completely empty.
I checked cable connections, settings, firmware… everthing fine. But I recognized that the dynamic cut-off page in the ess assistant is missing in the older/without gx multiplus.
New Update:
After it was below minimum SoC and got load, inverter switched to pass-thru and never came out of it. Only after I rebooted the cerbo then it switched back to discharging. Anything is weird in the cerbo, maybe some issues with the firmware (v3.66).
I replace the cerbo with a new one and will keep you informed.
I’m seeing very similar behaviour on my 3-phase system after updating to GX v3.66 and Multi firmware 510.
In my case L2 and L3 remain in import / pass-through even though voltages, CTs, Dynamic Cut-Off, Assistants and the Pylontech US3000C BMS are all correct.
The system shows no VE.Bus error, and the behaviour is stable until I remove all Assistants — then everything works normally again.
Once the Assistants are added back, L2/L3 go into import again.
My second installation, with the same hardware and the same Assistant setup, but still running firmware 502, works perfectly — so the issue may be related to the newer firmware or ESS logic, similar to what you described.
I will reconfigure everything from scratch and also check VE.Bus configuration with MK3 next week.
Would be great to hear if you observe the same behaviour on GX 3.66.